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How to Tell a Boy Red-Eared Turtle From a Girl

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Red-eared sliders (Trachemys scripta elegans) are some of the most frequently spotted turtles around, in their natural sluggish-water environments as well as in captive habitats. If you come across one of these family Emydidae creatures in the wild, you might be able to confound your pals by specifying the sex. Boy and girl red-eared sliders have some sexual dimorphism and therefore look somewhat different -- though both sexes have the signature red markings close to their eyes.


Size difference is a convenient means of telling boy and girl red-eared sliders apart. The females tend to be bigger than the males, but not too significantly. When mature, female red-eared sliders generally achieve 10 to 13 inches in length. Adult male red-eared sliders typically get to somewhere in the range of 8 and 10 inches long. For size to be a useful means of determining sex, though, you have to know turtle's approximate ages. Other factors make this a less-than-100-percent effective means of sexing red-eared sliders.


Pay attention to these midsize turtles' claws. The boys have extended claws in the front. They make the most of these claws when wooing females for breeding purposes. Male red-eared sliders attempt to lure females by lightly prodding their heads. When mating actually is going on, the males seize the females' upper shells by employing their claws, too. This typically occurs in warm times of the year. Reproductive activities for red-eared sliders generally happen in March, April, May, June and July.

Upper Shells

Red-eared sliders' upper shells, or carapaces, also often look somewhat different from each other. Individuals of both sexes have level upper shells, oval in form, although these qualities are often considerably more pronounced in the boys.


Red-eared sliders of both sexes have mostly green bodies, although with lots of noticeably vivid yellow streaking all over. With the aging process, many red-eared sliders take on a dark, close to blackish appearance. This darkening of coloration is particularly prevalent in the males, so if you ever happen upon a particularly dark red-eared slider, then he's likely a boy. Significant darkening often leads to lack of visibility of any yellow color elements.


Male and female red-eared slider tails also can denote sex. Male tails not only are a lot lengthier than the female tails, they're also a bit wider. If a specimen is on the small side but has a pretty big tail at the same time, you might feel comfortable guessing that he's indeed a boy.